This invention relates to communication control equipment, and particularly to a high speed protocol processing apparatus for processing a layered communication protocol having a plurality of layers.
In general, when the layered communication protocol of a seven-layer OSI model is processed, a particular layer (for example, layer 2 or above) protocol is processed by hardware of high-speed LSIs, and the other-layer (layer 3 or above) protocol is processed by a general-purpose CPU using software.
The reason for this is that the communication protocol processing is complicated, and the protocol processor is required to have a general-purpose applicability for various different protocols and a flexibility for application to various different network environments.
In other words, heretofore, it was difficult to process a complicated communication protocol by hardware having a general-purpose applicability and flexibility.
One example of the system for processing the layered communication protocol at high speed is proposed in, for example, JP-A 62-117050, in which a protocol processor is provided for each layer so that a layered protocol is processed by a pipe-line system, thereby achieving a high throughput.
In the above protocol processor, a plurality of microprocessors are used so that one protocol processor processes one-layer protocol. In addition, the operation of each microprocessor is controlled by a microprogram down-loaded from an external device.
According to the conventional protocol processor, however, although a high throughput can be obtained as compared with the processor for processing all layers using a single microprocessor, it is difficult to greatly reduce the protocol processing time because the protocol of each layer is processed by one processor for each layer in a software manner.